Competing interests: The author has declared that no competing interests exist.

Because of the nature of the analysis used in this study [1], no conclusion is possible. There are plenty of examples in the literature demonstrating the “ecological fallacy”. Studies such as this have very little utility other than to generate hypotheses. I tend to think that this association is a marker for greater recognition and treatment for depression. However, it’s a brave epidemiologist who would draw any conclusions at all from an ecological association such as this where the outcome is relatively rare.